Probably because old calendars (such as the Persian Calendar) used 360 days for a year-when they watched the stars they saw them revolve around the North Star one degree per day.
September 27, 2015 will bring a supermoon lunar eclipse at nightfall. The last lunar eclipse of this magnitude occurred in 1982, and the next one of a similar magnitude will be in 2033. A lesser lunar eclipse will come in 2018. The lunar eclipse part of this phenomenon, according CTV, is caused by the Earth inserting itself between the sun and the moon. As this happens, the Earth casts its shadow on the face of the moon.
Not to be confused with Solar eclipse. A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth and moon are aligned (in syzygy) exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon.